Sam Spanovich asked that I do a write-up on how I got my electronic ignition to work. The SDS CPI electronic ignitions that he and I are using in our KR2S VW engines are really a great piece of technology well worth looking into. Here is how I got my system to work... Though our systems are identical, Sam and I took different approaches as to "How to" install them. The difference between Sam's installation and mine was the location of the magnets and sensors. Sam placed his magnets and sensors in the rear of his engine, while mine are mounted in the front. Sam's installation made sense because he purchased his electronic ignition while his engine was still disassembled on his bench. This gave him the freedom to machine the necessary parts and place them in the back of his case. Conversely, my engine was already installed on my airplane with a dual magneto still attached... so this is where Sam and I parted ways as far as the "how to" do the installation. I must say that at this time, there were only two other installations of this type on a VW aircraft engine using the SDS CPI system. Sam's installation and a gentleman that had installed his on a Q2 with a Revmaster engine. Sam's setup would not work for me because of the reasons mentioned above, so I studied the Q2's installation. I liked the idea of using the propeller bolts to hold the magnets and his bracket design to hold the sensors; however, I did not want welds on my brackets. I made several cardboard mockups of brackets to study the best-supporting structure that would also be free of vibrations. This structure should also provide the necessary geometry to place my sensor within .068" from the magnets. These magnets were drilled onto the end of the propeller bolts in a pattern that offered the best timing solution for operating the engine...Several interactions later I was able to build a bracket that was vibration free and offered the best geometric solution for the flying magnets and sensors. The biggest problem left to solve was magnet sequencing (timing). I had to find a timing resolution between the magnets, the sensor, and the firing sequence of the engine (computer). The book had some great examples but those examples were for clockwise turning Lycoming, Continental, and Jabiru engines. My Revmaster turned counter-clockwise. I once again reached out to the Q2 guy but he said he didn't remember what he had used. The factory gave me some general solutions but I could not get them to work mainly because the propeller bolts are spaced 60° from each other,.and no other angular placement would work. So I studied the relationship between the magnet positions and the sensors. I needed magnet trigger #1 to fly past the sensor at approximately 90° from TDC. I knew that the computer would add 10° of advance. therefore the firing solution was to fire cylinder #1 at a cumulative delay of 100° from the sensor. As I said before, I could only set my magnets at 60° increments, I program the magnetic position on the computer to 90°. This translated into 60° actual and 30° theoretical. I then selected the bolt that was closest to TDC and I placed magnet trigger #1 there. By doing this TDC and trigger #1 were timed to each other. Every time trigger #1 passed the sensor, it triggered a delay of 90° plus 10° advance and the engine fired precisely at 10°BTDC. I then attached a timing light to tweak the timing and I settled at a magnet position of 104° from the sensor. I was ok with that because all of my settings were estimated positions and the timing light brought everything into sync. Presently, the system is working like a charm. My bracket is vibration free and solid as a rock. I am working with a machinist to fabricate a more permanent frame but for now, it.s working Luis R Claudio, KR2S N8981S
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